学校まで行くバスは、一時間に一本しかなかったので、学校にときどき遅刻をしてしまうことがありました。
Hello, I don't know what the 1 book is doing in the middle of this sentence form my 新完全マスター語彙日本語能力試験N3 book.
My meaning: "On the way to school it takes 1 hour and I have nothing to do but read one book on the way there."
I know it's wrong, but what else can you do with a book other than read it??